In a plasma processing apparatus configured to perform a process such as a plasma etching process on a semiconductor wafer (hereinafter, referred to as “wafer”), for example, the wafer accommodated in a container is transferred into a plasma processing chamber which is maintained in a vacuum atmosphere by using a transfer device (transfer robot).
In general, the plasma processing apparatus includes multiple plasma processing chambers, and a single transfer device is configured to access to these multiple plasma processing chambers. As an example of such a transfer device, there is used a transfer device equipped with a transfer arm having a multi-joint structure in which multiple arm members are rotatably connected via joint units. This transfer device is configured to access to the multiple plasma processing chambers by changing intersecting angles between the arm members through rotation at the joint units.
In this transfer device, a pick is provided at a leading end of the arm member at a leading end side thereof, and the wafer is transferred while being placed on the pick. To suppress the wafer from being separated or falling down from the pick, there is proposed a pick equipped with an electrostatic attracting device configured to attract and hold the wafer electrostatically (see, for example, Patent Document 1).
Patent Document 1: Japanese Patent Laid-open Publication No. 2011-077288
The conventional multi-joint transfer device equipped with the pick having the electrostatic attracting device is provided with a cable through which a power is supplied to the electrostatic attracting device from a base of the transfer device along the arm. In this regard, it is required to secure an extra length of a cable in the vicinity of each joint unit so that the cable may not be cut in the state that the arm members are bent at maximum angles. In other words, a rotational angle at the joint unit may be limited depending on the cable length. Further, since the extra cable provided at the joint unit is bent repeatedly as the rotation at the joint unit is repeated, there may be a problem in durability of the cable.